System and method for protection of printed images formed on surfaces of three-dimensional printed objects

ABSTRACT

A method of forming a three-dimensional printed object having a printed surface image includes ejecting drops of a build material to form the three-dimensional printed object with a plurality of layers of build material and at least one layer of a transparent material. The method operates ejectors to form a printed image with a marking agent so the printed image can be viewed through the at least one transparent layer. A leveler is applied to a surface of the layer of transparent material but not to the printed image.

PRIORITY CLAIM

This application is a divisional application of and claims priority toU.S. patent application Ser. No. 14/569,622, which is entitled “SystemAnd Method For Protection Of Printed Images Formed On Surfaces OfThree-Dimensional Objects,” which was filed on Dec. 12, 2014, and whichissued as U.S. Pat. No. x,xxx,xxx on mm/dd/yyyy.

TECHNICAL FIELD

This disclosure is directed to three-dimensional object printing systemsand, more particularly, to systems and methods of forming printed imageson surfaces of objects that are produced in a three-dimensional objectprinter.

BACKGROUND

Three-dimensional printing, also known as additive manufacturing, is aprocess of making a three-dimensional solid object from a digital modelof virtually any shape. Many three-dimensional printing technologies usean additive process in which successive layers of the part are built ontop of previously deposited layers. Some of these technologies useinkjet printing, where one or more printheads eject successive layers ofmaterial. Three-dimensional printing is distinguishable from traditionalobject-forming techniques, which mostly rely on the removal of materialfrom a work piece by a subtractive process, such as cutting or drilling.

Many existing three-dimensional printers form the printed objects usingone or more build materials with little or no regard to the appearanceof the surface of the object. However, some three-dimensional objectprinters also form two-dimensional printed images on a surface of thethree-dimensional printed objects. The printer forms two-dimensionalimages on the object to improve the aesthetics of the three-dimensionalprinted object and to convey information such as printed instructions,part labels, barcodes, and the like.

Printed images that are formed on the surface of a three-dimensionalprinted object are susceptible to damage both during and after thethree-dimensional printing process. Consequently, improved systems andmethods for the protection of printed images on the surfaces ofthree-dimensional printed objects would be beneficial.

SUMMARY

In one embodiment, a method of forming a two-dimensional image on asurface of a three-dimensional printed object has been developed. Themethod includes operating with a controller a first plurality ofejectors to eject drops of a build material to form thethree-dimensional printed object with a plurality of layers of the buildmaterial on a support member, applying a leveler to a surface of thethree-dimensional printed object after forming each layer in theplurality of layers of the build material, operating with the controllera second plurality of ejectors to eject drops of a marking agent on asurface of the three-dimensional printed object to form a printed image,operating with the controller a third plurality of ejectors to ejectdrops of a transparent material over the printed image to form a layerof transparent material over the printed image, and applying the levelerto a surface of the layer of transparent material without applying theleveler to the printed image prior to formation of the layer oftransparent material over the printed image.

In another embodiment, a three-dimensional object printer that isconfigured to form a two-dimensional image on a surface of athree-dimensional printed object has been developed. Thethree-dimensional object printer includes at least one printhead, aleveler, a support member, and a controller operatively connected to theat least one printhead and the leveler. The at least one printheadincludes a first plurality of ejectors configured to eject drops of abuild material, a second plurality of ejectors configured to eject dropsof at least one marking agent, and a third plurality of ejectorsconfigured to eject drops of a transparent material. The controller isconfigured to operate the first plurality of ejectors to eject drops ofthe build material to form the three-dimensional printed object with aplurality of layers of the build material on the support member, applythe leveler to a surface of the three-dimensional printed object afterforming each layer in the plurality of layers of the build material,operate the second plurality of ejectors to eject drops of the markingagent on a surface of the three-dimensional printed object to form afirst printed image, operate a third plurality of ejectors to ejectdrops of a transparent material over the first printed image to form afirst layer of transparent material over the first printed image, andapply the leveler to a surface of the first layer of transparentmaterial without applying the leveler to the first printed image priorto formation of the first layer of transparent material over the firstprinted image.

In another embodiment, a method of forming a three-dimensional printedobject with a printed image using a three-dimensional object printer hasbeen developed. The method includes operating with a controller a firstplurality of ejectors to eject drops of a transparent material onto asupport member to form a layer of transparent material on the supportmember, applying a leveler to a surface of the layer of transparentmaterial, operating with the controller a second plurality of ejectorsto eject drops of a marking agent onto the surface of the layer oftransparent material to form a printed image, operating with thecontroller a third plurality of ejectors to eject drops of a buildmaterial over the printed image to form a layer of build material in athree-dimensional printed object, and applying the leveler to a surfaceof the layer of the build material without applying the leveler to theprinted image prior to formation of the layer of the build material overthe printed image.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing aspects and other features of an apparatus or printer thatgenerates two-dimensional printed images on a surface of athree-dimensional printed object are explained in the followingdescription, taken in connection with the accompanying drawings.

FIG. 1 is a diagram of a three-dimensional object printer.

FIG. 2 is a block diagram of a process for operation of athree-dimensional object printer to form two-dimensional images with aprotective layer on a surface of a three-dimensional printed object.

FIG. 3 is a block diagram of a process for operation of athree-dimensional object printer to form two-dimensional images with aprotective layer on a bottom surface of a three-dimensional printedobject.

FIG. 4 is a cross-sectional view of a portion of a printed image formedon a surface of a three-dimensional printed object with a protectivelayer of transparent material.

DETAILED DESCRIPTION

For a general understanding of the environment for the device disclosedherein as well as the details for the device, reference is made to thedrawings. In the drawings, like reference numerals designate likeelements.

As used herein, the term “build material” refers to a material that isejected in the form of liquid drops from a plurality of ejectors in oneor more printheads to form layers of material in an object that isformed in a three-dimensional object printer. Examples of buildmaterials include, but are not limited to, thermoplastics, UV curablepolymers, and binders that can be liquefied for ejection as liquid dropsfrom ejectors in a printhead and subsequently hardened into a solidmaterial that forms an object through an additive three-dimensionalobject printing process. Some three-dimensional object printerembodiments employ multiple forms of build material to produce anobject. In some embodiments, different build materials with varyingphysical or chemical characteristics form a single object. In otherembodiments, the printer is configured to eject drops of a single typeof build material that incorporates different colors through dyes orother colorants that are included in the build material. Thethree-dimensional object printer controls the ejection of drops of buildmaterials with different colors to form objects with varying colors andoptionally with printed text, graphics, or other single and multicolorpatterns on the surface of the object.

As used herein, the term “process direction” refers to a direction ofmovement of a support member past one or more printheads during athree-dimensional object formation process. The support member holds thethree-dimensional object during the print process. In some embodiments,the support member is a planar member such as a metal plate, while inother embodiments the support member is a rotating cylindrical member ora member with another shape that supports the formation of an objectduring the three-dimensional object printing process. In someembodiments, the printheads remain stationary while the support memberand object moves past the printhead. In other embodiments, theprintheads move while the support member remains stationary. In stillother embodiments, both the printheads and the support member move.

As used herein, the term “cross-process direction” refers to a directionthat is perpendicular to the process direction and in the plane of thesupport member. The ejectors in two or more printheads are registered inthe cross-process direction to enable an array of printheads to formprinted patterns of build material over a two-dimensional planar region.During a three-dimensional object printing process, the printheads ejectdrops of the build material to form successive layers of build materialthat form a three-dimensional object.

As used herein, the term “primer material” refers to a material thatforms a durable coating over another surface to form an image receivingsurface for ink or another marking agent. In some embodiments, theprimer is a white material that forms a white background for a printedimage, although other primer materials have a wide range of colors inaddition to white. The primer forms a surface that promotes the adhesionof marking agents to form printed images on a surface of athree-dimensional printed object.

As used herein, the term “marking agent” refers to any material that canbe formed on a surface of an object to form visible marks includingmonochrome and color printed images that include text and graphics.Examples of marking agents include various forms of ink, includingaqueous, solvent based, and phase-change inks. Other forms of markingagent include toner compounds. In some embodiments, the printer forms aprinted image including a layer of the marking agent formed over a layerof the primer to promote adhesion and visibility of the marking agent.

As used herein, the term “z-axis” refers to an axis that isperpendicular to the process direction, the cross-process direction, andto the plane of the support member in a three-dimensional objectprinter. At the beginning of the three-dimensional object printingprocess, a separation along the z-axis refers to a distance ofseparation between the support member and the printheads that form thelayers of build material in a three-dimensional printed object. As theejectors in the printheads form each layer of build material, theprinter adjusts the z-axis separation between the printheads and theuppermost layer to maintain a substantially constant distance betweenthe printheads and the uppermost layer of the object during the printingoperation. In some embodiments, the support member moves away from theprintheads during the printing operation to maintain the z-axisseparation, while in other embodiments the printheads move away from thepartially printed object and support member to maintain the z-axisseparation.

FIG. 1 depicts a three-dimensional object printer 100 that is configuredto operate printheads to form a three-dimensional printed object 150 andto form a printed image 154 on a surface of the object 150. The printer100 includes a support member 102, printhead arrays 104A-104C,106A-106C, 108A-108C, and 110A-110C, an ultraviolet (UV) curing device112, actuator 124, controller 128, memory 132, and a leveler 172. FIG. 1depicts the three-dimensional object printer 100 during formation of athree-dimensional printed object 150 from a plurality of layers of thebuild material using the printhead array 104A-104C. The printer 100 alsoforms a printed image 154 using the printhead array 110A-110C with atransparent protective layer over the printed image formed using theprinthead array 106A-106C.

In the embodiment of FIG. 1, the support member 102 is a planar member,such as a metal plate, that moves in a process direction P. The leveler172, printhead arrays 104A-104C, 106A-106C, 108A-108C, and 110A-110C;and UV curing device 112, form a print zone 120. The member 102 carriesany previously formed layers of build material through the print zone120 in the process direction P. During the printing operation, thesupport member 102 moves in a predetermined process direction path Pthat passes the printheads multiple times to form successive layers ofthe build material in the object 150, primer layers on the surface ofthe object 150, and the printed image 154 on the surface of the primerlayers on the object 150. In some embodiments, multiple members similarto the member 102 pass the print zone 120 in a carousel or similarconfiguration. One or more actuators move the member 102 through theprint zone 120 in the process direction P. In the embodiment of FIG. 1,an actuator also moves the support member 102 in the direction Z awayfrom the components in the print zone 120 after each layer of buildmaterial is applied to the support member 102. The actuator moves thesupport member 102 in the Z direction to maintain a uniform separationbetween the uppermost layer of the object 150 and the components in theprint zone 120.

In the configuration of FIG. 1, the printhead array 104A-104C ejectsdrops of a build material toward the surface of the support member 102to form layers of a three-dimensional printed object, such as the object150. The printheads 104A-104C are arranged in a staggered configurationto enable a two-dimensional array of ejectors in each printhead to ejectdrops on a portion of the support member 102. The printheads 104A-104Care arranged in a “stitched” configuration to enable the ejectors in theprintheads 104A-104C to form a continuous arrangement of the buildmaterial across the support member 102 in the cross-process directionCP. While FIG. 1 depicts an array of three printheads, alternativeconfigurations include a greater or lesser number of printheads.

Each of the printheads 104A-104C includes a plurality of ejectors thatreceive the build material in a liquefied form and eject liquid drops ofthe build material. In one embodiment, each ejector includes a fluidpressure chamber that receives the liquid build material, an actuatorsuch as a piezoelectric actuator, and an outlet nozzle. Thepiezoelectric actuator deforms in response to an electric firing signaland urges the liquefied build material through the nozzle as an ejecteddrop that travels toward the member 102. If the member 102 bearspreviously formed layers of a three-dimensional object, then the ejecteddrops of the build material form an additional layer of the object. Eachof the printheads 104A-104C includes a two-dimensional array of theejectors, with an exemplary printhead embodiment including 880 ejectors.During operation, the controller 128 controls the generation of theelectrical firing signals to operate selected ejectors at differenttimes to form each layer of the build material for the object 150. Inthe printer 100, the controller 128 operates the ejectors in theprintheads 104A-104C with reference to the 3D object image data 134 thatare stored in the memory 132 to apply the build material.

In the printer 100, the printhead arrays 106A-106C, 108A-108C, and110A-110C each include three printheads with the same or similarconfigurations to the printheads 104A-104C, but each of the printheadarrays ejects a different type of material. In the illustrative exampleof FIG. 1, the ejectors in the printhead array 106A-106C eject drops ofa transparent material that forms a protective transparent layer overprinted images that are formed on the surface of the object 150. In oneembodiment, the transparent material is a transparent phase-change inkthat the ejectors in the printheads 106A-106C eject as liquid drops. Thetransparent phase-change ink solidifies over the printed image 154 inresponse to the UV radiation from the curing device 112 to form aprotective layer of transparent material. The printhead array 108A-108Ceject drops of a primer material, such as a white primer material, thatform a layer over the surface of the build material to receive drops ofa marking agent in a printed image. The printhead array 110A-110C ejectsdrops of at least one color of marking agent to form printed images onan image receiving surface that is formed from a layer of the primermaterial on the three-dimensional printed object 150. For example, theejectors in the printhead array 110A-110C eject drops of cyan, magenta,yellow, and black (CMYK) inks to form multicolor images. FIG. 1 depictsa single printhead array 110A-110C that ejects drops of the markingagent for simplicity, but alternative embodiments include multipleprinthead arrays that eject different ink colors to form multicolorprinted images.

While FIG. 1 depicts four printhead arrays that eject drops of the buildmaterial, transparent material, primer, and colored ink, alternativeembodiments can include three or more printhead arrays that form printedobjects with additional build materials. Another embodiment includesonly a single printhead array. While the printhead arrays 104A-104C,106A-106C, 108A-108C, and 110A-110C are each depicted as including threeprintheads, alternative configurations can include few printheads or agreater number of printheads to accommodate print zones with differentsizes in the cross-process direction. Alternative embodiments caninclude additional printhead arrays, such as additional color inkprinthead arrays or printhead arrays that emit different types of buildmaterial. While the printhead arrays 104A-104C, 106A-106C, 108A-108C,and 110A-110C remain stationary during operation in the printer 100,alternative printer embodiments include one or more printheads that movein the cross-process direction CP, process direction P, or in both thecross-process and process directions to form a three-dimensional printedobject.

In the printer 100, the UV curing device 112 is an ultraviolet lightsource that produces UV light across the print zone 120 in thecross-process direction CP. The UV light from the UV curing device 112hardens the build material that is formed on the uppermost layer of theobject 150 to form a durable portion of the object 150. The UV curingprocess solidifies the build material to accept additional layers ofbuild material or coatings that form an image receiving surface for atwo-dimensional printed image on an exterior of the three-dimensionalprinted object 150.

As use herein, the term “leveler” refers to a member that is configuredto engage the uppermost surface of each layer of the build materialbefore the UV curing device 112 cures the build material. In the printer100, the leveler 172, which is also referred to as a planarizer, appliesa heated surface to the object 150. The heated surface of the leveler172 softens or melts a portion of the uppermost layer of the buildmaterial in the object 150. The leveler 172 also applies pressure tosmooth the uppermost layer of build material in the object 150 and forma uniform surface that receives an additional layer of the buildmaterial during a subsequent pass through the print zone 120. In someembodiments, the leveler 172 is a roller that is coated with a lowsurface energy material to prevent adhesion of the build material to thesurface of the leveler 172. While the other components in the print zone120 remain at a predetermined distance in the Z direction from theobject 150, the leveler 172 is configured to engage the object 150 tosmooth the uppermost layer.

In the configuration of FIG. 1, the leveler 172 engages the uppermostlayer of build material, primer or transparent protective materialformed in the object 150, but does not engage layers of image markingink on the surface of the object 150 to enable the printer 150 to formthe printed image 154 on the outer surface of the object 150. In oneembodiment, the controller 128 operates an actuator to increase thez-axis distance between the support member 102 and the components in theprint zone 120 during formation of the printed image to prevent theleveler 172 from engaging the marking agent in the printed image. Inanother embodiment, the controller 128 operates another actuator that isoperatively connected to the leveler 172 to move the leveler 172 out ofengagement with the object 150 while the printer 100 forms the printedimage 154 on the surface of the object 150.

The actuator 124 is an electromechanical device, such as a steppermotor, that is configured to control the position of the support member102 along the z-axis. During a three-dimensional printing operation, theactuator 124 adjusts the z-axis position of the support member 102 tomaintain a predetermined distance between the upper layer of the printedobject 150 and the components in the print zone 120. As described inmore detail below, the actuator 124 moves the support member 102 awayfrom the leveler 172 along the z-axis by a predetermined distance whilethe printer 100 forms the printed image 154 on the surface of the object150 to prevent the leveler 172 from engaging the ink in the printedimage 154. The actuator 124 also moves the support member 102 toward theleveler 172 along the z-axis after the printer 100 forms a protectivelayer of transparent material over the printed image to enable theleveler 172 to smooth the transparent material layer. In the printer100, the controller 128 is operatively connected to the actuator 124.

The controller 128 is a digital logic device such as a microprocessor,microcontroller, field programmable gate array (FPGA), applicationspecific integrated circuit (ASIC) or any other digital logic that isconfigured to operate the printer 100. In the printer 100, thecontroller 128 is operatively connected to one or more actuators thatcontrol the movement of the support member 102, the printhead arraysincluding the printhead arrays 104A-104C, 106A-106C, 108A-108C, and110A-110C, and the UV curing device 112. The controller 128 is alsooperatively connected to a memory 132. In the embodiment of the printer100, the memory 132 includes volatile data storage devices such asrandom access memory (RAM) devices and non-volatile data storage devicessuch as solid-state data storage devices, magnetic disks, optical disks,or any other suitable data storage devices. The memory 132 storesthree-dimensional (3D) object image data 134, two-dimensional (2D)printed image data 136, and stored program instructions 138. Thecontroller 128 executes the stored program instructions 138 to operatethe components in the printer 100 to both form the three-dimensionalprinted object 150 and print two-dimensional images on one or moresurfaces of the object 150. The 3D object image data 134 includes, forexample, a plurality of two-dimensional image data patterns thatcorrespond to each layer of build material that the printer 100 formsduring the three-dimensional object printing process. The controller 128ejects drops of the build material from the printheads 104A-104C withreference to each set of two-dimensional image data to form each layerof the object 150. The memory 132 also stores two-dimensional image data136 that correspond to a printed image that the printer 100 forms on thesurface of the three-dimensional printed object 150 using one or morecolors of marking agent from the printheads in the array 110A-110C.

During operation, the controller 128 operates the ejectors in theprintheads 104A-104C to form the three-dimensional printed object 150from the build material with reference to the three-dimensional imagedata 134. The leveler 172 engages each layer of the build material inthe object 150 as the support member 102 moves the object 150 throughthe print zone 150 in the process direction P. After printing at least aportion of the three-dimensional printed object 150, the controller 128operates the ejectors in the printhead array 110A-110C to form theprinted image 154 on a surface of the printed object 150. The controller128 optionally operates the ejectors in the printhead array 108A-108C toform one or more layers of the primer material over the build materialin the object 150 prior to forming the printed image with the printheadarray 110A-110C.

The controller 128 operates the actuator to move the support member 102and upper layer of the object 150 away from the leveler 172 along thez-axis to prevent the leveler 172 from contacting the marking agent inthe printed image 154. For example, in one embodiment the actuator 124moves the support member 102 away from the leveler by a distance ofapproximately 0.5 mm to 1 mm along the z-axis to prevent application ofthe leveler to the ink in the printed image 154. The actuator 124 alsomaintains a suitable z-axis distance between the printheads 110A-110Cand the object 150 to form the printed image 154.

After forming the printed image 154, the controller 128 operates theprinthead array 106A-106C to form a layer of transparent material overthe printed image 154. The transparent material solidifies to form aprotective layer over the printed image 154. In the printer 100, thecontroller 128 operates the actuator 124 to move the upper layer oftransparent material upward on the z-axis to apply the leveler 172 tothe surface of the layer of transparent material. The leveler 172 formsa smooth uniform surface on the layer of transparent material.

FIG. 2 depicts a process 200 for forming a three-dimensional printedobject with a two-dimensional image printed on a surface of the object.In the discussion below, a reference to the process 200 performing anaction or function refers to the operation of a controller to executeprogram instructions to perform the task or function in conjunction withother components in a three-dimensional object printer. The process 200is described in conjunction with the printer 100 of FIG. 1 and the viewof the printed object 150 in FIG. 4 for illustrative purposes.

During process 200, the printer 100 forms the three-dimensional printedobject 150 from a plurality of layers of the build material and theprinter 100 applies the leveler 172 to each layer of the build materialto maintain a uniform upper surface for the object 150 (block 204).During operation, the controller 128 operates the ejectors in theprinthead array 104A-104C to form each layer of the build material withreference to the three-dimensional object image data 134. The actuator124 positions the support member 102 and the previously formed layers ofbuild material in the object 150 along the z-axis to enable the leveler172 to apply heat and pressure to the uppermost layer of build material.The printer 100 forms the plurality of layers and applies the leveler172 to each layer until the object 150 has formed a surface that canreceive the printed image 154. The leveler 172 maintains the uppersurface of the object 150 with a uniform height along the z-axis.

The process 200 continues as the printer 100 optionally operates theejectors in the printhead array 108A-108C to form a layer of the primermaterial on the surface of the object 150 (block 208). As describedabove, the printer material forms an image receiving surface for dropsof the marking agent, such as ink drops, that form a printed image onthe surface of the object 150. Some printer embodiments do not use aprimer material and eject drops of the marking agent onto the buildmaterial in the object 150 directly.

The process 200 continues as the controller 128 operates the ejectors inthe printheads 110A-110C to form the printed image 154 on the surface ofthe object 150 without applying the leveler 172 to the printed image 154(block 212). In the printer 100, the controller 128 operates theactuator 124 to move the support member 102 and printed object 150 awayfrom the leveler 172 and other components in the print zone 120 alongthe z-axis prior to operating the ejectors in the printheads 110A-110Cto form the printed image 154 on the surface of the object 150. Theuppermost layer of build material in the object 150 forms the imagereceiving surface for the image 154 in one configuration, or the layerof the primer material forms the image receiving surface in aconfiguration that use a primer material.

The controller 128 operates the ejectors in the printhead array110A-110C to form the printed image 154 using one or more of the CMYKinks with reference to the 2D image data 136. The printer 100 also curesthe material in the printed image 154 using, for example, the UV lightsource 112 or by enabling the printed marking agent to dry or solidifyon the surface of the object 150. The actuator 124 moves the supportmember and object 150 away from the leveler 172 by a sufficient distancealong the z-axis to prevent the surface of the leveler 172 from beingapplied to the printed image 154 on the surface of the object 150. Theheated surface of the leveler 172 produces smearing or other artifactsin the marking agent that forms printed image 154 if the leveler 172engages the printed image 154. The controller 128 adjusts the positionof the support member 102 along the z-axis to maintain a z-axisseparation between the marking agent in the printed image 154 and theleveler 172. In some embodiments, the support member 102 and object 150pass the printhead array 110A-110C two or more times during a multi-passprinting process to form the printed image 154, and the leveler 172 doesnot engage the object 150 during the multi-pass printing process.

Process 200 continues as the printer 100 operates the ejectors in theprinthead array 106A-106C to form a layer of transparent material overthe printed image 154 and applies the leveler 172 to the transparentlayer to form a smooth surface for the transparent material layer (block216). The printer 100 optionally moves the support member 102 throughthe print zone 120 one or more times to form the layer of transparentmaterial with varying levels of thickness. In some embodiments, thetransparent material forms a comparatively thin (e.g. 100 μm to 1 mm)protective layer over the printed images. In other embodiments, thetransparent material is also a build material that forms a portion ofthe printed object, and the printer 100 forms multiple layers of thetransparent material having any thickness up to a maximum thicknesswithin the operating parameters of the printer 100. As described above,the transparent material forms a protective layer over the marking agentthat forms the printed image 154. The transparent material enables theprinted image to remain visible while protecting the printed image 154from damage through contact with the leveler 172 during the printingprocess or from other damage that could occur to the finished object 150after completion of the process 200. In the illustrative embodiment ofFIG. 2, the printer 100 applies the leveler 172 to the surface of thetransparent material after forming the layer of transparent material andprior to curing the layer with the UV curing device 112 to form aprotective layer over the printed image 154. The controller 128 operatesthe actuator 124 to move the support member 102 and object 150 towardthe leveler 172 along the z-axis to apply the heated surface of theleveler 172 to the layer of transparent material after formation of thetransparent layer of material over the printed image 154. The leveler172 applies heat and pressure to the surface of the transparent materialto produce a smooth surface of the transparent material layer.

During process 200, the printer 100 also cures the transparent materialafter the leveler 172 has formed a smooth surface of the transparentmaterial layer (block 220). In the embodiment of FIG. 1, the transparentmaterial is UV curable and the UV curing device 112 applies UV radiationto the transparent material on the surface of the object 150 to cure thetransparent material. The curing device 112 applies UV radiation toharden the smoothed surface of the transparent material layer to form adurable protective coating over the printed image.

In the process 200, the three-dimensional object printer 100 forms atwo-dimensional printed image on a surface of a three-dimensionalprinted object. In some embodiments, the three-dimensional objectprinter 100 forms an image on a bottom surface of an object and formsthe three-dimensional object over the printed image instead of formingthe image on a surface of a previously printed three-dimensional object.FIG. 3 depicts a process 300 for forming a three-dimensional printedobject with a two-dimensional image printed on a bottom surface of theobject. In the discussion below, a reference to the process 300performing an action or function refers to the operation of a controllerto execute program instructions to perform the task or function inconjunction with other components in a three-dimensional object printer.The process 300 is described in conjunction with the printer 100 of FIG.1 and the view of the printed object 150 in FIG. 4 for illustrativepurposes.

Process 300 begins as the printer 100 forms a layer of transparentmaterial on the surface of the support member 102 (block 304). In theprinter 100, the controller 128 operates the printheads 106A-106C toform a layer of transparent material on the surface of the supportmember 102. In some configurations, the printheads 106A-106C form athicker layer of transparent material during multiple passes of thesupport member 102 through the print zone 120. After completion of theprocess 300, the lower surface of the transparent material that engagesthe surface of the support member 120 may be polished, buffed, orotherwise smoothed during a finishing process. The finishing process mayremove a portion of the transparent material, and the printer 100optionally forms a thicker layer of transparent material to accommodatethe finishing process. The printer 100 applies the leveler 172 to smooththe surface of transparent material prior to forming a printed image onthe surface of the transparent layer that faces the printheads in theprint zone 120 (block 308).

Process 300 continues as the printer 100 forms a printed image over thelayer of transparent material without engaging the leveler to themarking agent in the printed image (block 312). In some configurations,the controller 128 inverts the two-dimensional image data 136 for theprinted image so that text and other graphics appear to be arranged inan expected direction when viewed from the bottom of the completedthree-dimensional printed object 150. The controller 128 operates theejectors in the marking agent printheads 110A-110C to form the printedimage in one or more passes over the layer of transparent material. Theprinter 100 does not apply the leveler 172 to the marking material thatforms the printed image in a similar manner to the formation of theprinted image during process 200. The printer 100 optionally cures themarking material with the UV curing device 112.

Process 300 continues as the printer 100 optional prints one or morelayers of primer material over the surface of the printed image (block316). The controller 128 operates the ejectors in the printhead array108A-108C to form one or more layers of the primer material over theprinted image. The printer 100 applies the leveler 172 and UV curingdevice to the primer material layer. Process 300 continues as theprinter 100 prints layers of the build material over the layers oftransparent material, the printed image, and the primer using theprintheads 104A-104C (block 320). In some configurations, the printer100 does not form a separate layer of primer material and the controller128 forms one or more layers of the build material directly over theprinted image. While printing the layers of build material, the printer100 applies the leveler 172 to some or all of the layers of buildmaterial to maintain a uniform upper surface of the object 150 duringthe printing process. In some configurations, the printer 100 completesprinting of the three-dimensional object 150 and performs the process200 to form another printed image on an upper surface of the object 150.

FIG. 4 depicts the layers of material in the printed object 150including an upper layer 424 that is formed from the build material orthe primer material, the marking agent that forms the printed image 154,and the layer of transparent material 428. As described above, duringthe process 200, the leveler 172 is applied to the outer surface of thetransparent material layer 428, but the printer 100 operates theactuator 124 to position the object 150 along the z-axis to prevent thesurface of the leveler 172 from being applied to the marking agent inthe printed image 154. FIG. 4 also depicts a printed image 432 that isformed on the bottom surface of the three-dimensional printed object150. As described above, the printer 100 performs process 300 to form alayer of transparent material 436, the printer 100 then forms theprinted image 432 over the transparent material layer 436 withoutapplying the leveler 172 to the marking agent in the printed image 432.The printer 100 then applies an optional layer of primer material andcontinues printing build material 424 to form the object 150 over theprinted image layer 432.

It will be appreciated that variants of the above-disclosed and otherfeatures and functions, or alternatives thereof, may be desirablycombined into many other different systems, applications or methods.Various presently unforeseen or unanticipated alternatives,modifications, variations or improvements may be subsequently made bythose skilled in the art that are also intended to be encompassed by thefollowing claims.

What is claimed:
 1. A method of forming a three-dimensional printedobject with a three-dimensional object printer comprising: operatingwith a controller a first plurality of ejectors to eject drops of afirst material to form at least one layer of the first material on asupport member; applying a leveler to a surface of the at least onelayer of the first material after forming each layer of the at least onelayer of the first material; operating with the controller a secondplurality of ejectors to eject drops of a marking agent on the leveledsurface of the at least one layer of the first material to form aprinted image on the leveled surface of the at least one layer of thefirst material; operating with the controller a third plurality ofejectors to eject drops of a second material over the printed image toform at least one layer of the second material over the printed image,the second material being different than the first material; andapplying the leveler to a surface of the at least one layer of thesecond material without applying the leveler to the printed image beforea first layer of the second material was formed over the printed image.2. The method of claim 1 wherein the first material is a build materialand the second material is a transparent material.
 3. The method ofclaim 2, the operation of the first plurality of ejectors furthercomprising: operating the first plurality of ejectors with thecontroller to form the three-dimensional object with a plurality oflayers of the build material.
 4. The method of claim 3, the operation ofthe second plurality of ejectors further comprising: operating thesecond plurality of ejectors with the controller to form the printedimage on a surface of the three-dimensional object.
 5. The method ofclaim 4, the operation of the third plurality of ejectors furthercomprising: operating the third plurality of ejectors to form a singlelayer of transparent material over the printed image.
 6. The method ofclaim 5 further comprising: operating with the controller a fourthplurality of ejectors to eject drops of a primer material onto thesurface of the plurality of build layers prior to operating the secondplurality of ejectors to form the printed image.
 7. The method of claim6 further comprising: operating with the controller an actuator toadjust a distance between the leveler and the surface of the pluralityof build layers prior to operation of the second plurality of ejectorsto prevent the leveler from being applied to the printed image.
 8. Themethod of claim 7 further comprising: operating with the controller theactuator to adjust the distance between the leveler and the single layerof the transparent material after operation of the third plurality ofejectors to apply the leveler to the single layer of transparentmaterial.
 9. The method of claim 8 further comprising: operating withthe controller a curing device to cure the transparent material afterformation of the layer of transparent material over the printed imageand after application of the leveler to the surface of the layer oftransparent material.
 10. The method of claim 1 wherein the firstmaterial is a transparent material and the second material is a buildmaterial.
 11. The method of claim 10, the operation of the firstplurality of ejectors further comprising: operating the first pluralityof ejectors with the controller to form a single layer of thetransparent material on the support member.
 12. The method of claim 11,the operation of the second plurality of ejectors further comprising:operating the second plurality of ejectors with the controller to formthe printed image on a surface of the single layer of the transparentmaterial.
 13. The method of claim 12, the operation of the thirdplurality of ejectors further comprising: operating the third pluralityof ejectors to form at least one layer of build material over theprinted image.
 14. The method of claim 13 further comprising: operatingwith the controller a fourth plurality of ejectors to eject drops of aprimer material onto the printed image prior to operating the thirdplurality of ejectors.
 15. The method of claim 14 further comprising:operating with the controller an actuator to adjust a distance betweenthe leveler and the layer of transparent material on the support memberprior to operation of the second plurality of ejectors to prevent theleveler from being applied to the printed image.
 16. The method of claim15 further comprising: operating with the controller the actuator toadjust the distance between the leveler and the at least one layer ofthe build material formed over the printed image after operation of thethird plurality of ejectors to apply the leveler to a surface of the atleast one layer of build material.